Patent Literature 1 (WO2011/078189) discloses a hybrid vehicle capable of driving in either an EV driving mode that drives an electrical motor only by electric power of a storage battery or a series drive mode that drives an electrical motor by electric power generated by a power generator with movement power of an internal combustion engine (see claim 1). Further, Patent Literature 1 discloses controlling in such a manner as to derive a required driving force of the electrical motor, based on the vehicle speed and the accelerator pedal open degree, make determination of a start of the internal combustion engine and determine the power generation amount of the power generator, from the required driving force and the state of the storage battery, thus making the vehicle in the EV driving mode or in the series driving mode (see claim 1 and FIG. 4).
Patent Literature 2 (JP 09-224304 A) discloses a hybrid vehicle that has movement power sources of two systems, which are an internal combustion engine and an electrical motor, and appropriately selects driving only the electrical motor, driving only the internal combustion engine, or simultaneous driving of the electrical motor and the internal combustion engine (see claim 2). Also, disclosed is that the internal combustion engine is driven at a constant rotation speed at the best fuel economy point, and a battery is charged by generating power with an output surplus of the internal combustion engine during driving only the internal combustion engine (see claim 2 and see FIG. 3).